diff --git a/clientv3/integration/kv_test.go b/clientv3/integration/kv_test.go
index f9f87fe20a8..49f107f76df 100644
--- a/clientv3/integration/kv_test.go
+++ b/clientv3/integration/kv_test.go
@@ -381,6 +381,36 @@ func TestKVRange(t *testing.T) {
 				{Key: []byte("fop"), Value: nil, CreateRevision: 9, ModRevision: 9, Version: 1},
 			},
 		},
+		// fetch entire keyspace using WithFromKey
+		{
+			"\x00", "",
+			0,
+			[]clientv3.OpOption{clientv3.WithFromKey(), clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend)},
+
+			[]*mvccpb.KeyValue{
+				{Key: []byte("a"), Value: nil, CreateRevision: 2, ModRevision: 2, Version: 1},
+				{Key: []byte("b"), Value: nil, CreateRevision: 3, ModRevision: 3, Version: 1},
+				{Key: []byte("c"), Value: nil, CreateRevision: 4, ModRevision: 6, Version: 3},
+				{Key: []byte("foo"), Value: nil, CreateRevision: 7, ModRevision: 7, Version: 1},
+				{Key: []byte("foo/abc"), Value: nil, CreateRevision: 8, ModRevision: 8, Version: 1},
+				{Key: []byte("fop"), Value: nil, CreateRevision: 9, ModRevision: 9, Version: 1},
+			},
+		},
+		// fetch entire keyspace using WithPrefix
+		{
+			"", "",
+			0,
+			[]clientv3.OpOption{clientv3.WithPrefix(), clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend)},
+
+			[]*mvccpb.KeyValue{
+				{Key: []byte("a"), Value: nil, CreateRevision: 2, ModRevision: 2, Version: 1},
+				{Key: []byte("b"), Value: nil, CreateRevision: 3, ModRevision: 3, Version: 1},
+				{Key: []byte("c"), Value: nil, CreateRevision: 4, ModRevision: 6, Version: 3},
+				{Key: []byte("foo"), Value: nil, CreateRevision: 7, ModRevision: 7, Version: 1},
+				{Key: []byte("foo/abc"), Value: nil, CreateRevision: 8, ModRevision: 8, Version: 1},
+				{Key: []byte("fop"), Value: nil, CreateRevision: 9, ModRevision: 9, Version: 1},
+			},
+		},
 	}
 
 	for i, tt := range tests {
diff --git a/clientv3/op.go b/clientv3/op.go
index e8218924ba3..63b99501e82 100644
--- a/clientv3/op.go
+++ b/clientv3/op.go
@@ -282,6 +282,10 @@ func getPrefix(key []byte) []byte {
 // can return 'foo1', 'foo2', and so on.
 func WithPrefix() OpOption {
 	return func(op *Op) {
+		if len(op.key) == 0 {
+			op.key, op.end = []byte{0}, []byte{0}
+			return
+		}
 		op.end = getPrefix(op.key)
 	}
 }